You seem to be making the assumption that English is as popular and widely used as C. I would like to remind you that it is only the case in western parts of the world, which is by far, not the majority.
I think it's a reasonable assumption. The people who can speak English, whether as a first, second or foreign language, is about 1.5 billion.[1] Comparable to Mandarin speakers.[2] So, about 20% of all humans.
What proportion of developers can write C at an analogous level to first, second or foreign language? 20% seems like quite a good ball park estimate, from my (anecdotal) experience.
Note that the numbers for English are from 2006, the numbers for Mandarin (960 Million) are from 2010 and they lump together all the different (not mutually intelligible) dialects of Mandarin.
Noted, but it doesn't detract from my point about C. The number of Mandarin speakers was only to refute the OP's assertion that an anglocentric view of the world biases the opinion of how popular English is as a world language; this is not the case, it is genuinely popular.
Everyone in China learns English now, and a lot of the Far East has English (or Panglish, Singlish etc) as a major language. And it's pretty popular in India.
Nor sayng it's perfect and universal, but it is pretty widespread even outside "The West"
What proportion of developers can write C at an analogous level to first, second or foreign language? 20% seems like quite a good ball park estimate, from my (anecdotal) experience.
[1] https://en.wikipedia.org/wiki/English_language
[2] https://en.wikipedia.org/wiki/Mandarin_Chinese